Over 80,000 Veterans with Parkinson?s disease (PD) currently obtain their medical care within the VA Healthcare System, and the number of Veterans with PD is expected to increase considerably in the near future. Health-related Quality of Life (HRQoL) is severely compromised in those with PD and worsens as the disease progresses. Non-motor symptoms, particularly impaired cognition and mood (anxiety and depression), contribute to poor and worsening of HRQoL in PD. Therefore, interventions that target these symptoms and improve HRQoL are critically needed. Mindfulness-based Stress Reduction (MBSR) in a non-pharmacological intervention that has been shown to improve HRQoL, mood, and cognition in older adults with and without neurological conditions. Although preliminary evidence supports MBSR as a promising intervention for PD, a systematic, comprehensive randomized controlled trial (RCT) of MBSR has yet to be conducted in this population. Moreover, it is unknown if immediate preliminary benefits are maintained over time. As PD is a neurodegenerative disorder, non-transient benefits are of paramount importance in the treatment of this chronic, disabling disease. Results from our pilot trial (n = 20) demonstrated that PD participants who completed an 8-week MBSR program (n = 8) evidenced an improvement in overall HRQoL (d? = 1.1), cognition (d? = 1.6), and mood (anxiety; d? = 1.1), compared to PD participants in an 8-week active control condition (Psychoeducation/Supportive Care; n = 12); the latter of whom experienced a worsening of symptoms. These findings provide compelling preliminary evidence of MBSR efficacy for PD, and strongly underscore the need for adequate treatment of PD-related non-motor symptoms with empirically-validated interventions. The overall aim of this longitudinal RCT is to determine the efficacy of MBSR to improve HRQoL, cognition, and mood, as well as to determine the longevity of the treatment response in individuals with PD. We hypothesize that HRQoL, cognition (particularly executive function), and mood (particularly anxiety) symptoms (will improve in PD participants following eight weeks of MBSR compared to PD participants randomized to an eight-week active Psychoeducation control condition. We further hypothesize that benefits of MBSR treatment will be evident at the 6- and 12-month assessments, such that those completing the MBSR group will demonstrate better HRQoL, cognition, and mood relative to those PD patients who completed the Psychoeducation/Supportive Care (PSC) group. Potential mediators/moderators of the treatment response will be examined in exploratory hypotheses. Eighty-eight non-demented individuals with PD will be recruited and enrolled in the proposed study. Over-recruitment by 10% will be instituted to account for subject attrition or unusable data, and to ensure an adequately-powered sample size of 80 (40 per group). Participants will be randomized into either eight of weeks of MBSR (n = 44) or eight weeks of PSC (n = 44). All participants will be administered a battery of neuropsychological tests to measure HRQoL, cognition (e.g., executive function, attention, memory), and mood (i.e., anxiety, depression, and apathy), as well as motor symptoms, disease severity, and mindfulness engagement/practice. Tests will be administered at baseline, 8 weeks (post-treatment), and 6- and 12-months (follow-up assessments) by an examiner blinded to group assignment. Data will be primarily analyzed using linear and multivariable random effects modeling. Findings from this study will provide critical information regarding the efficacy of MBSR for HRQoL, cognition, and mood in PD. Furthermore, results will provide essential data regarding the long-term benefits of MBSR in PD, and elucidate potential mediators/moderators of treatment response. Ultimately, this study will contribute to the VA mission by establishing an empirically-validated intervention for Veterans and civilians with PD that can be easily and widely implemented and disseminated throughout the VA Healthcare System.